Hitherto, as an apparatus for measuring a change in pressure to be measured, there is known a pressure change measuring apparatus including an inner chamber (pressure chamber), a differential pressure gauge (diaphragm or the like) configured to measure a pressure difference between a pressure of the inner chamber and the pressure to be measured, and a pressure through hole configured to allow a pressure transmission medium for transmitting the pressure to be measured to flow into and out of the inner chamber (see, for example, PTLs 1 and 2).
The pressure through hole has extremely small structure, and restricts the flowing of the pressure transmission medium into the inner chamber. Further, the pressure within the inner chamber changes depending on an amount of the pressure transmission medium flowing into and out of the inner chamber, and hence the pressure within the inner chamber follows the change in pressure to be measured with a delay. Therefore, the pressure difference between the pressure of the inner chamber and the pressure to be measured is measured, to thereby be able to detect the change in pressure to be measured.